February 1, 2011 - Sky & Telescope
Anyone who's been to a group observing session recently knows how valuable green lasers have become to our enjoyment of stargazing. Those pencil-thin beams of light allow us to point out objects in the sky and even to aim our telescopes effortlessly. (Of course, some idiots insist on pointing them at aircraft, a dangerous practice that's a huge disservice to those of us who use them responsibly.)
At the professional level, the stakes are higher and the toys bigger. Many major observatories already have — or are developing — systems that use powerful lasers to project pinpoints of light high in the atmosphere. These serve as artificial guide stars for adaptive-optics systems that correct for less-than-ideal "seeing" (atmospheric turbulence). When everything works, celestial targets can be recorded with astonishing clarity.
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